The present invention relates to a cooling system for an engine.
Conventionally, known cooling systems for vehicles form a plurality of coolant flow paths passing through an engine body (cylinder head or cylinder block) or auxiliary machinery (heater core, exhaust gas recirculation (EGR) device, etc.), and are provided with a flow rate control valve for controlling coolant flow rates of the respective coolant flow paths (e.g., JP2013-224643A). Such a cooling system restricts the flow of the coolant into the engine body via the flow rate control valve while the engine is being warmed up after a cold start so as to stimulate a temperature increase of the engine body. When the temperature of the coolant within the coolant path passing through the cylinder head is increased, the cooling system cancels the flow restriction of the coolant into the engine body so as to cool the engine body.
However, in the engine to which the cooling system of JP2013-224643A is applied, there is a time-lag until the temperature change of the cylinder head is reflected in the temperature change of the coolant. Therefore, the temperature of the cylinder head may excessively increase during the time-lag, and the cylinder head may be damaged.